I was going to say that.
Even within historical sources, the context of when they were written matters - this a contemporary source is more important than one written 200 years later even if supported by evidence. Because of the reflection of the time.
The same is true of sci fi. The majority of sci fi of the 1960s is very positive and very progressive and forward looking whereas a lot of the sci currently being made has huge amounts of theme revolving around the concept of the end of times and dystopia.
It's a reflection of the mood of times and the current politics.
This isn't a good or bad thing as such.
But if you are using historical drama as a means to increase equality you have to be very careful about whether you are creating narratives which destroy understanding of the reality of struggles due to inequality. You can inadvertently do more harm than good if you create an idea that the real historical story has been in someway exaggerated.
Imagine doing a story about Auschwitz but saying we can't make it so bad because that wouldn't be kind to the Germans and it might make them look bad. Or perhaps saying we need to add more representation of black people to the story because otherwise it's not inclusive. There would be people who took certain messages from that which would undermine actual understanding of history and not reflect reality. This is, of course, this problem taken to it's very extreme but it helps to highlight the problem.
If the cultural value is it's historical nature, then take that on board and take the responsibility of that seriously. Otherwise make it such a juxtaposition that it's obvious and clear to the audience that this is a modern take on the story which wishes to be inclusive and of its time.
There's room for inclusivity here, without reducing it to, 'well what if the black kids take from it that their role in society is only to be a slave'. In some ways that's patronising anyway, because they might NEED to understand as part of their modern understanding of where they've come from and how history has shaped the lives of their family that yes actually, that WOULD have been your life experience if born in a different era.
The desire to push inclusivity into everything in an unthinking way is what I take a beef with. It very much can have counter productive outcomes if done badly. There is room for inclusion here, but it has to be done in a careful and thoughtful manner. Not just willynilly.